A new approach uses the standard GUID_DEVINTERFACE_COMPORT and
GUID_DEVINTERFACE_MODEM GUID's which shall be used for the development
of any serial port drivers. Besides requires adding of the additional
DIGCF_DEVICEINTERFACE flag for the SetupDiGetClassDevs() function,
see MSDN:
http://msdn.microsoft.com/en-us/library/windows/hardware/ff551069%28v=vs.85%29.aspx

Thus, it seems effective to use both "Setup Class GUID" and
"Device Interface Class GUID" approaches that will complement each
other. In this case can be keep only the standard GUID's.

1. Now all GUID classes are in the QUuid form and stored in the
constant list of pairs as QPair<uuid, flags>. It allows to avoid the
old heritage related to the pure-C coding style.

2. The second "flags" parameter from the pair is the DWORD input
parameter for the SetupDiGetClassDevs() function which specify the
control options that filter the device information elements. It
allows to pass the appropriate flags for the each used approach
independently.

Tested with the cenumerator example on Windows with Qt4 and then Qt5,
no regressions found.